1. Field of the Invention
The present invention relates to a recording timing setting apparatus for setting recording timing (recording position) at the time of recording recording information in a recording medium such as an optical disk, and an information recording apparatus including the recording timing setting apparatus.
2. Description of the Related Art
Recently, a DVD-R/W having an improved recording density of as much as several times that of a CD-R (compact disk-recordable) as a conventional recordable optical disk has been developed. The DVD-R/W can record recording information many times. That is, recording information can be recorded in a portion on a DVD-R/W wherein recording information is not recorded (hereinafter referred to as “addition recording”), or other recording information can be overwritten in a portion on a DVD-R/W wherein recording information is already recorded (hereinafter referred to as “overwrite recording”).
A plurality of pits are arranged on a DVD-R/W discretely (hereinafter referred to “prepits”). The prepits are recorded on a DVD-R/W preliminarily in the state that no recording information is recorded. For example, in a conventional DVD-R/W, prepits are formed as phase pits on a land track adjacent to a groove track in which recording information is to be recorded.
Prepits are synchronization signals to be used for recording recording information in a DVD-R/W. That is, in recording the recording information on the DVD-R/W, an information recording apparatus generates a synchronization signal based on the prepits and generates a recording clock to be the standard for recording the recording information based on the synchronization signal as well as obtains address information showing the position on the DVD-R/W at which the recording information is to be recorded. The recording information is recorded in the DVD-R/W according to the recording clock and the address information.
The recording performance of the DVD-R/W can be improved by preliminarily recording the synchronization signal to be used for the record of the recording information in the DVD-R/W as prepits. That is, even if the rotation of the DVD-R/W is displaced from the steady rate due to disturbance, the frequency of a recording clock signal can be displaced corresponding to the displacement. Accordingly, a recording clock signal having a frequency always synchronous with the rotation of the DVD-R/W can be generated, and thus recording information can be recorded accurately.
However, at the time of executing addition recording, sometimes the synchronization signal cannot be generated accurately by inability of detecting prepits due to flaw or finger prints on the surface of the DVD-R/W. In this case, since generation of the recording clock signal is interrupted temporarily, recording information cannot be recorded accurately at the desired recording position.
On the other hand, at the time of overwrite recording of recording information, a signal including both signal corresponding to the prepits and signal corresponding to the recording information already recorded on the DVD-R/W is detected from the DVD-R/W. Therefore, it is difficult to detect only the signal corresponding to the prepits. As a result, the synchronization signal may not be detected accurately.